But new research from the University of Otago has found six minutes of high intensity exercise may help maintain a healthy brain, and delay the onset of neurodegenerative disorders such as Parkinson’s and Alzheimer’s.
The research, led by former University of Otago physical education, sport and exercise sciences researcher Dr Travis Gibbons, focused on a protein called brain-derived neurotrophic factor (BDNF), which is essential in memory formation and storage.
He discovered short bursts of high intensity exercise, increased production of the neuro-protective protein.
Dr Gibbons said while research using animal models had shown increased BDNF promoted growth and survival of neurons in the brain and slowed brain-specific ageing processes, there had been limited research exploring strategies of how to naturally increase the protein in humans.
Using 12 physically active participants — six males and six females, aged between 18 and 56 — researchers compared four conditions to examine which was most effective at increasing the protein in the blood.
"We compared fasting for 20 hours, light exercise (90 minutes of low intensity cycling), high intensity exercise (6 minutes of vigorous cycling) and combined fasting and exercise.
"We found that the brief, intense exercise was the most efficient means to increase BDNF in the blood, and it did so by four to five-fold, compared with only a slight increase with low intensity exercise, and no change with fasting."
Dr Gibbons said it was not yet clear why this happened, but researchers suspected it was related to the brain switching from using glucose as its primary fuel, to using lactate which is produced during high intensity exercise.
"This ‘substrate switch’ allows the brain to utilise alternative fuels and initiates the production of key neurotrophic factors such as BDNF.
"Another possibility is related to the 20% increase in the concentration of circulating platelets that occurs with exercise, as platelets store a large amount of BDNF."
He said scientists were now studying how fasting for longer durations — up to three days — with and without intense exercise, influenced BDNF.
"Fasting and exercise are rarely studied together, and we think the combination may optimise the production of BDNF."
Spokes Dunedin chairman Jon Deans said the research added yet another benefit to cycling.
"There’s been a lot of research over the years on the benefits of exercise and the benefits of high intensity training.
"Anecdotally, it does not surprise me that it has neurological benefits.
"Here’s one more tranche of a benefit to cycling."
Senior author and University of Otago department of surgical sciences researcher Dr Kate Thomas said these protocols may sound demanding, but the work would help researchers better understand the natural production of BDNF.
"It is becoming more and more clear that exercise benefits brain health at all stages of life.
"These data show one avenue by which intense exercise may play a role.
"Fortunately, exercise is widely accessible, equitable and affordable."
